The overall aim of this project is the investigation of the neurobiological basis of reasoning and decision-making, guided by a specific theoretical framework, the "somatic marker hypothesis". The hypothesis posits that decision-making defects in the personal and social realms are the result of defective engagement of emotion related signals ("somatic markers") that normally operate, covertly or overtly, to facilitate the process of making advantageous choices. In the current funding period, we have investigate anatomical, physiological, and cognitive aspects of a neural network presumed to underlie somatic marker activation and decision making. We confirmed that dysfunction in the ventromedial (VM) prefrontal cortex leads to a failure to enact somatic states and to decision-making defects. However, lesions in other neural regions, including the amygdala and the somatosensory cortices (SII, SI, and insula) also compromise somatic state activation and decision-making, suggesting that these several regions are part of a neural system involved in decision-making. Guided by the results obtained so far, the new studies we propose aim at defining the functional roles played by these components, and by others we propose here. The studies call for the testing of several hypotheses of several hypotheses using the lesion approached in cognitive and psychophysiological experiments. Disorders of decision-making are A prominent feature of the "dysexecutive syndrome" seen in stroke, head injury, and brain tumors. Such disorders are also prevalent in drug addiction, psychopathy, and borderline personality disorder. Our results will contribute to the understanding of normal and pathological mechanisms of decision- making and lead to the development of novel behavioral and pharmacological management strategies.